A rotary electric machine such as a power generator, an electric motor or the like generally uses a laminated core formed by laminating thin plate materials such as magnetic steel sheets. At the laminated core, a coil is wound around respective projecting pole portions or permanent magnets are embedded therein, and such laminated core is applied at a rotor, a stator or the like. In a manufacturing process of the laminated core, a predetermined number of plate materials, formed in an annular shape by means of punching, are laminated in an axial direction of the laminated core. Because a thickness of each plate material may vary, the laminated core is manufactured in such a way that plate materials are laminated so as to reach a target lamination thickness of the laminated core, not on the basis of a target number of the plate materials to be used, and the number of the plate materials to be used for forming the laminated core is controlled to be increased or decreased so as to reach the target lamination thickness of the laminated core. Further, instead of using the annular shaped plate materials having relatively low yield rates, arc shaped unit cores, each corresponding to a part of the annular shaped plate material and having high yield rate, are formed, and a windingly laminated core is produced by arranging the arc shaped unit cores so as to be windingly laminated in a circumferential direction and in a spiral manner.
JP2007-68310A discloses an example of the windingly laminated core. The windingly laminated core disclosed in JP2007-68310A, having a first number of magnetic poles in total, is configured by a predetermined number of unit cores that are windingly limited, each of the unit cores formed in an arc shape and having a second number of magnetic poles, the second number being a natural number except for an aliquot part of the first number. The predetermined number of unit cores are partially connected to each other at an outer circumferential surface thereof. The partially connected unit cores are windingly laminated continuously to form the windingly laminated core, thereby reducing the time required for manufacturing the core. Further, because the number of the magnetic poles to be provided at each of the unit cores is the second number that is not an aliquot part of the first number, contacting surface positions at which the unit cores are contacting each other in a circumferential direction are not aligned in an axial direction of the core, in other words, the unit cores are formed in a staggeringly windingly laminated core, in which a mechanical strength is relatively high.
According to the windingly laminated core disclosed in JP2007-68310A, when the predetermined number of unit cores are windingly laminated in such a way that a rotational phase of a start of a winding lamination is aligned to a rotational phase of an end of the winding lamination, because of differences of plate thicknesses of the unit cores, the lamination thickness of the windingly laminated core may not reach a predetermined thickness. Even when the number of the unit cores is adjusted in order to reach the predetermined lamination thickness, the rotational phase of the start of the winding lamination may not be aligned to the rotational phase of the end of the winding lamination, which means the windingly laminated core includes different numbers of unit cores and different lamination thicknesses in a circumferential direction. Such windingly laminated core is not suitable for practical use of the rotor because a level of a balance around an axis of the core is reduced. In this circumstance, additional unit cores are arranged so as to be windingly laminated in order to exceed the predetermined thickness and to align the rotational phase of the start of the winding lamination and the rotational phase of the end of the winding lamination. However, in a case where a large number of windingly laminated cores are manufactured, a lamination thickness of each of the cores may vary within (second number −1) number at a maximum, and further, because the lamination thickness of the windingly laminated core substantially exceeds the predetermined thickness, a length of the rotary electric machine in an axial direction thereof may be increased. Furthermore, the used amount of the plate materials is increased.
JP2007-68310A also discloses that, in order to align the rotational phases of the first and the end of the winding lamination, an adjustment unit core, formed so as to have a third number of magnetic poles, is arranged at the start or the end of the winding lamination, the third number being a natural number smaller than the second number, however, a manufacturing method of the adjustment unit core is not disclosed in JP2007-68310A.
A need thus exists to provide a windingly laminated core of a rotary electric machine and a manufacturing method thereof, which is not susceptible to the drawback mentioned above.